Make bcpc_cephconfig provider idempotent
Make bcpc_cephconfig provider idempotent

This rewrites the cephconfig provider in the following ways:
- makes it idempotent by correctly comparing the value
- flattens out the pyramid of ifs by adding a few nexts
- drops some error handling that was not likely to ever be reached

mihalis68/chef-bcpc,semenovroman/chef-bcpc,mihalis68/chef-bcpc,bloomberg/chef-bcpc,semenovroman/chef-bcpc,bloomberg/chef-bcpc,bloomberg/chef-bcpc,mihalis68/chef-bcpc,semenovroman/chef-bcpc,semenovroman/chef-bcpc,mihalis68/chef-bcpc,mihalis68/chef-bcpc,bloomberg/chef-bcpc,semenovroman/chef-bcpc